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Clonal Structure (clonal + structure)
Selected AbstractsSexual or clonal origin?FEDDES REPERTORIUM, Issue 3-4 2005A morpho-ecological, molecular analysis in a patch of Ajuga reptans L. (Lamiaceae) Spatial clonal structure and patch colonisation in Ajuga reptans L. (Lamiaceae), a common stoloniferous semi-rosette plant, were studied using a combined morpho-ecological and molecular genetic approach. Within a natural patch from a forest near Diedorf (Thuringia, Germany), the spatial clonal structure was analysed, correlating both datasets: Morphologically, characteristics of clonal growth and clonal reproduction were studied, the spatial distribution of modules was mapped and merigenet relationships were reconstructed. Samples from the patch and its surroundings, and an additional sample from Berlin were then analysed by AFLP fingerprinting using four different primer combinations to identify genets. Most divergence in banding patterns was already obtained for samples from the Diedorf forest. Within the patch, however, most samples had very similar fingerprints, indicating their belonging to the same genet and hence a clonal origin, although they are morphologically separated into three "plants". Based on AFLP data, the relationships of one sample remained ambiguous; but the correlation with morphological data helped to interpret the pattern and indicated that the sample is probably a dividual of the clone, too. The relevance of the observed vegetative multiplication (clonal growth and subsequent clonal reproduction) for patch colonisation and maintenance are discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Generativer (sexueller) oder klonaler Ursprung? Eine morpho-ökologische und molekulare Analyse in einem ,patch' von Ajuga reptans L. (Lamiaceae) Die räumliche klonale Struktur und die ,patch' Besiedlung von Ajuga reptans L. (Lamiaceae), einer häufigen Halbrosettenpflanze mit Ausläufern, wurden mit einem morpho-ökologischen und molekular-genetischen Ansatz kombiniert analysiert. Die Untersuchung wurde in einem ,patch' aus einem Wald bei Diedorf (Thüringen) durchgeführt: Morphologisch wurden Merkmale des klonalen Wachstums und der klonalen Reproduktion untersucht, die räumliche Verteilung der Module kartiert und Merigenet-Beziehungen rekonstruiert. Für Proben aus dem ,patch', aus dessen näherer Umgebung und einer Pflanze aus Berlin wurden AFLP Analysen mit vier verschiedenen Primer-Kombinationen durchgeführt, um genetische Individuen (Genets) zu identifizieren. Die meisten Unterschiede in den Fragmentmustern zeigten sich bereits zwischen Proben aus Diedorf. Die ,patch'-Proben (morphologisch aufgeteilt in drei "Pflanzen") hatten jedoch sehr ähnliche fingerprints, was ihre Zugehörigkeit zum selben Genet und eine klonale Abstammung belegt. Für eine Probe ließen sich die Verwandtschaftsbeziehungen mit den AFLP Daten nicht sicher klären. Der Abgleich mit den morphologischen Ergebnissen ermöglichte jedoch eine Interpretation, und deutet auf die Zugehörigkeit zum Klon. Die Bedeutung der "vegetativen Multiplikation" (durch klonales Wachstum und klonale Reproduktion) für die Besiedlung und dauerhafte Besetzung von ,patches' wird diskutiert. [source] Molecular Variability of Mycosphaerella graminicola as Detected by RAPD MarkersJOURNAL OF PHYTOPATHOLOGY, Issue 10 2004M. Razavi Abstract A total of 90 isolates of Mycosphaerella graminicola, the cause of septoria tritici leaf blotch of wheat, were tested for DNA polymorphism using 15 decamer random primers. There was a high level of genetic variability among isolates. In 131 random amplified polymorphic DNA (RAPD) fragments, which were produced, 96% were polymorphic. Based on multilocus analysis, 40 different molecular phenotypes were detected. These molecular phenotypes were randomly distributed among sampling sites, suggesting that no clonal structure existed in the population. Cluster analysis showed that the maximum similarity value among isolates was approximately 81% and no identical isolates were detected, indicating that every isolate was a unique genotype. The high degree of DNA polymorphism, the large number of different molecular phenotypes, their random distribution and the results of the cluster analysis all suggested that sexual reproduction has a major role in the genetic structure of M. graminicola in western Canada. The presence of sexual reproduction provides the opportunity for development of new virulent genotypes in the population and suggests that the pathogen may adapt rapidly to any race-specific sources of resistance. Therefore, when breeding for resistance to M. graminicola, emphasis should be placed on use of non-race-specific resistance. [source] Direct measurement of spatial autocorrelation at the community level in four plant communitiesJOURNAL OF VEGETATION SCIENCE, Issue 6 2000Maia Mistral Abstract. Four sites were sampled to determine spatial autocorrelation in vegetation at the community level. All were in western New Zealand, but on different substrates and of different physiognomy: a terrace forest, a floodplain forest, a mire and the middle of a logging road. In ,dissimograms'the four communities all showed steady increases in dissimilarity with distance, but with shoulders in the curve for some sites, which could be related to plant morphology. Most of the increase in dissimilarity occurred over very short distances: less than 0.5 m in the forests, less than 1 m in the mire and less than 2 m in the road. Separate analyses of the woody and herbaceous guilds in the floodplain forest showed that herbaceous dissimilarities remained low at distances up to 20 m, probably because of clonal structure in some species. The mire showed low overall dissimilarity, which is attributed to the uniform substrate and the small species pool. Simulations showed that the approach is capable of indicating structure when it is present. Although the dissimogram was clearest when analysing a simulated grid of patches, other types of simulated patchiness showed dissimograms that were clearly distinguishable from those obtained from the vegetation studied. The almost continuous rise in dissimilarity with distance found in the four sites offers no support to the Hierarchy theory, fitting much more closely the alternative Continuum theory. [source] Amplified fragment length polymorphism (AFLP) markers reveal that population structure of triploid dandelions (Taraxacum officinale) exhibits both clonality and recombinationMOLECULAR ECOLOGY, Issue 1 2000R. G. M. Van Der Hulst Abstract Highly variable amplified fragment length polymorphism (AFLP) fingerprints of triploid apomictic dandelions obtained from three localities in an area where diploids are lacking were analysed to infer the predominant modes of reproduction. The distribution of markers was analysed using character compatibility to infer whether many genotypes agree with a tree-like structure in the data set. The presence of incompatible character state combinations (matrix incompatibility; MI) was used as a measure of genetic exchange. The detection of overrepresented genotypes, of which some were widespread, confirmed asexual reproduction. Not all genotypes were overrepresented; approximately half of the genotypes in the three localities were found only once. Because, in terms of genotype frequencies, only a part of the genetic variation is described, more important aspects of the molecular data such as relationships between markers or genotypes have been studied. The analysis of character compatibility indicated a disagreement of the data with a clonal structure. Nearly all genotypes contributed to MI and this contribution varied considerably among genotypes in each sampled locality. A gradual decrease of matrix incompatibility upon successive deletion of genotypes showing the highest contribution to MI indicated that marker distribution of virtually all genotypes disagreed with a tree-like structure in the data. This result suggested that many genotypes were separated by one or more sexual generations. Consistent with this conclusion was the fact that markers that show a low probability of contributing to MI are different in every sampled locality, which is most easily explained as the result of recombination. Apparently, asexual reproduction has resulted in overrepresented, widespread genotypes but sexual recombination has also substantially contributed to genetic variation in the sites studied. [source] Influence of clonal growth on selfing rate in Vaccinium myrtillus L.PLANT BIOLOGY, Issue 5 2008T. Albert Abstract Clonal growth, which allows the multiplication of flowering shoots of the same genet, can lead to a large floral display and may thus increase the rate of selfing through geitonogamy as a consequence of an increase in the number of successively visited flowers. The aim of the present research was to analyse the combined effect of the diversity and intermingling of clones on the rate of selfing in Vaccinium myrtillus. Four mother plants were selected within patches characterised by contrasting clonal structure (low versus high number and intermingling of clones). The selfing rate was significantly lower for plants situated within patches characterised by a high number of intermingled clones (3%) than for plants situated in patches with a low number of clones (50%). Therefore, for this species suffering from inbreeding depression, an increase in the number or the intermingling of the clones could reduce the rate and the cost of geitonogamy and allow a large floral display to attract pollinators. We also found that the main pollinators, bumblebee queens, presented a foraging behaviour favouring geitonogamy, as their successive visits to flowers were quite short (89% of flights were 40 cm or less). [source] Role of sexual reproduction in the spread of an invasive clonal plant Solidago canadensis revealed using intersimple sequence repeat markersPLANT SPECIES BIOLOGY, Issue 1 2006MEI DONG Abstract Invasive species, second only to habitat loss as a cause of biodiversity loss, pose serious threats to native biodiversity and ecosystems. Little is known about the mechanisms that some exotic plants use to become invasive in their non-native ranges. Solidago canadensis, native to North America, was intentionally introduced to many countries where it has become an invasive plant. To understand the roles that reproductive mode plays in successful invasion of exotic plants, and the relative importance of sexual reproduction and clonal growth, the genetic diversity and clonal structure of two S. canadensis populations from Shanghai, China were investigated using intersimple sequence repeats. Samples were collected in a grid pattern with intervals of 2 m among adjacent individuals within the studied area (approximately 30 m × 30 m) for each population. Results showed that the percentages of polymorphic loci for the two populations were 97.9% and 96.5% and clonal diversity measured using the Simpson Diversity Index was 1.00 for both populations. No identical genotypes were found among the analyzed samples. It is suggested from this study that sexual reproduction facilitates the establishment of new S. canadensis populations, whereas clonal expansion maintains and enlarges the established populations. Thus, limiting sexual reproduction of S. canadensis may effectively control the invasion of this species. [source] Effects of Light on the Growth and Clonal Reproduction of Ligularia virgaureaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2008Man-Tang Wang Abstract Ligularia virgaurea is a perennial herb that is widely distributed in the alpine meadow on the eastern Qinghai-Tibet plateau. We investigated the patterns of growth and reproduction of L. virgaurea under two contrasting levels of light conditions for two continuous growing seasons. Our results showed that the light effects on the maximum relative growth rate, the shoot weight ratio and the root weight ratio differed between the two growing seasons. L. virgaurea reproduced initially through rhizome in the second growing season, rather than sexual reproduction. The proportion of genets with clonal reproduction decreased under shaded conditions. A minimum genet size should be attained for clonal reproduction to begin under the shaded conditions. There was a positive linear relationship between clonal reproduction and genet size. Light level affected the allocation of total biomass to clonal structures, with less allocation under the full natural irradiance than under the shaded conditions. There seemed to be a trade-off between vegetative growth and clonal reproduction under the full natural irradiance, in terms of smaller relative growth rates of genets with clonal reproduction than those without clonal reproduction. L. virgaurea emphasized clonal reproduction under the full natural irradiance, while the plant emphasized vegetative growth under the shaded conditions. [source] | ||||||||||